Subaru Legacy (2005 year). Manual - part 355

EN(H4DOTC)(diag)-189

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

BN:DTC P2102 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT LOW

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Erroneous idling
• Poor driving performance
• Engine stalls.

26

CHECK ELECTRONIC THROTTLE CON-
TROL GROUND CIRCUIT.
Measure the resistance between ECM connec-
tor and chassis ground.

Connector & terminal

(B137) No. 3 — Chassis ground:

Is the resistance less than 10 
Ω?

Go to step 27.

Repair the open 
circuit of harness.

27

CHECK ELECTRONIC THROTTLE CON-
TROL.
Measure the resistance between electronic 
throttle control terminals.

Terminals

No. 1 — No. 2:

Is the resistance less than 5 
Ω?

Go to step 28.

Replace the elec-
tronic throttle con-
trol.

28

CHECK ELECTRONIC THROTTLE CON-
TROL.
Move the throttle valve to the fully open and 
fully closed positions with fingers.
Check that the valve returns to the specified 
position when releasing fingers.

Does the valve return to the 
specified position? Specifica-
tion: 3 mm (0.12 in) from fully 
closed position

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H4DOTC)-
34, Engine Con-
trol Module 
(ECM).>

Replace the elec-
tronic throttle con-
trol.

Step

Check

Yes

No

EN(H4DOTC)(diag)-190

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

WIRING DIAGRAM:

EN-03524

SBF-7

B135

B:

B137

B136

D:

B362

B84

B138

B122

E1

B20

E57

C:

B135

B362

B20

B21

E57

B84

B122

B138

B137

B136

E

E

D6

B35

16

15

*

*

*

*

7
3

E2

B21

39

38

19

20

35

36

37

4

6

1

2

3

5

D4

D5

C35

C16

B1

B4

D1

D2

D3

C29

C18

5

8

7

6

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

1 2

7 8

3
4

5
6

1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21 22
23 24 25

34 35

36 37 38 39 40 41

48 49

50 51 52 53 54

42 43

44 45

46 47

26 27 28 29 30 31 32 33

1 2 3 4
5 6 7 8

1 2 3 4 5 6

1

2

7

8 9

5

6

3

4

10 11 12

19 20 21

29

30 31

13 14 15 16 17

27

28

18

22 23

24 25

26

1

2

7

8 9

5

6

3

4

10 11 12

19

20 21

29 30 31

13 14 15 16 17

27

28

18

22 23

24 25

26

32 33

34 35

1

2

8 9

5

6

3

4

10 11 12

19 20 21

29 30

31

13 14 15 16

17

27

28

18

22 23 24 25 26

7

32 33 34 35

B:

D:

C:

ECM

BATTERY

MAIN RELAY

ELECTRONIC
THROTTLE 
CONTROL RELAY

ELECTRONIC
THROTTLE 
CONTROL

*

: TERMINAL No. RANDOM ARRANGEMENT

EN(H4DOTC)(diag)-191

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to electronic throttle 
control relay terminals No. 5 and No. 6.
4) Measure the resistance between electronic 
throttle control terminals.

Terminals

(B362) No. 7 — (B362) No. 8:

Is the resistance less than 1 
Ω?

Go to step 2.

Replace the elec-
tronic throttle con-
trol relay.

2

CHECK POWER SUPPLY OF ELECTRONIC 
THROTTLE CONTROL RELAY.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic 
throttle control relay connector and chassis 
ground.

Connector & terminal

(B362) No. 8 (+) — Chassis ground (

−

):

(B362) No. 5 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 3.

Repair the open or 
ground short cir-
cuit of power sup-
ply circuit.

3

CHECK HARNESS BETWEEN ECM AND 
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Turn the ignition switch to ON.
4) Measure the voltage between electronic 
throttle control relay connector and chassis 
ground.

Connector & terminal

(B362) No. 6 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Repair the power 

supply short cir-
cuit of harness 
between ECM and 
electronic throttle 
control relay.

Go to step 4.

4

CHECK HARNESS BETWEEN ECM AND 
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic 
throttle control relay connector and chassis 
ground.

Connector & terminal

(B362) No. 6 — Chassis ground:
(B362) No. 7 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 5.

Repair the ground 
short circuit of har-
ness between 
ECM and elec-
tronic throttle con-
trol relay.

5

CHECK HARNESS BETWEEN ECM AND 
ELECTRONIC THROTTLE CONTROL RE-
LAY.
Measure the resistance between ECM connec-
tor and electronic throttle control relay connec-
tor.

Connector & terminal

(B135) No. 35 — (B362) No. 6:
(B137) No. 6 — (B362) No. 7:

Is the resistance less than 1 
Ω?

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H4DOTC)-
34, Engine Con-
trol Module 
(ECM).>

Repair the open 
circuit of harness 
between ECM and 
electronic throttle 
control relay.

EN(H4DOTC)(diag)-192

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

BO:DTC P2103 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT HIGH

DTC DETECTING CONDITION:
Immediately at fault recognition
WIRING DIAGRAM:

EN-03524

SBF-7

B135

B:

B137

B136

D:

B362

B84

B138

B122

E1

B20

E57

C:

B135

B362

B20

B21

E57

B84

B122

B138

B137

B136

E

E

D6

B35

16

15

*

*

*

*

7
3

E2

B21

39

38

19

20

35

36

37

4

6

1

2

3

5

D4

D5

C35

C16

B1

B4

D1

D2

D3

C29

C18

5

8

7

6

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

1 2

7 8

3
4

5
6

1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21 22
23 24 25

34 35

36 37 38 39 40 41

48 49

50 51 52 53 54

42 43

44 45

46 47

26 27 28 29 30 31 32 33

1 2 3 4
5 6 7 8

1 2 3 4 5 6

1

2

7

8 9

5

6

3

4

10 11 12

19 20 21

29

30 31

13 14 15 16 17

27

28

18

22 23

24 25

26

1

2

7

8 9

5

6

3

4

10 11 12

19

20 21

29 30 31

13 14 15 16 17

27

28

18

22 23

24 25

26

32 33

34 35

1

2

8 9

5

6

3

4

10 11 12

19 20 21

29 30

31

13 14 15 16

17

27

28

18

22 23 24 25 26

7

32 33 34 35

B:

D:

C:

ECM

BATTERY

MAIN RELAY

ELECTRONIC
THROTTLE 
CONTROL RELAY

ELECTRONIC
THROTTLE 
CONTROL

*

: TERMINAL No. RANDOM ARRANGEMENT